Arc-welding system



. 1 5,049 Oct. 11, 1927. K. HA D I,

ARC WELDI NG SYSTEM Filed June 5 926 2 Sheets-Sheet 1 FIE-E it A W/us Oct. 11,1927. l,645,@49 1 A. K. HARFORD ARC WELDING SYSTEM Filed June 5, 1926 2 Sheets-Sheek; 2

, fi a Patented Oct. 11,- 19.27.

UNITED srnxras PATENT OFFICE.

ALBERT K. HARFORD, OF OAKLAND, CALIFORNIA, ASSIGNOR TO NEW METAL PRODUCTS COMPANY, OF EMERYVILLE, CALIFORNIA, A CORPORATION OF CALIFORNIA.

ARC-WELDINQ SYSTEM.

Application filled June 3, 1926. Seria1No.' 113,404.

This invention relates generally to are Fig. 4 is a circuit diagram showing the welding systems in which a metallic elec operation of the mechanism. trode is employed for establishing an are 4 F 1g. is a view showing diagrammatically directly upon the work to be welded. the manner in which the device of this in- One type of welding system m common vention- Wlll control movement of the elecuse employs a metallic electrode in the form trodes so that itzwill pass over large irreguof a rod or wire which is moved across the larlties on the work surface. work to be welded. Generally inweldmg The device comprises generally a constant machines forwelding long joints, elther the feed motor'which is operatively connected 10 electrode support or the work is moved along to the electrode by means of an automatically a straight line andthe electrode is fed forcontrolled driving mechanism. The drive ward at a rate substantially equal to the from the motor is applied to the electrode rate of consumption. In order to autothrough a pair of clutches so that upon matically' control the rate of feed and thus engagement of one clutch the electrode is maintain a stable arc, it has been prevlously fed 1n one direction and upon engagement proposed to employa variable speed feed of the other clutch the electrode is moved motor and to control the speed of the same 111 the opposite. direction. Controlling in accordance with the condition of the arc. means s provided for actuating these This arrangement workswell as long as the Clutches alternately, the controlling means 2 surface of the work is plain, but is not satisbeing responslve to the potential variations factory whenthe surface is veryirregular across the arc. v as a condition may then occur in whlch the Referrmg to the drawings, the mechanism electrode must be withdrawn in order to prehas been shown as mounted upon a base v nt short circuiting of the arc. member 10 so that it may be conveniently in- It is an object of this invention to devise rporated 1n any suitable welding machine. an automatic feed mechanism for an arc elec- The drlvlng mechanismfor the metallic electrode which may be driven by a constant trode 11 comprises a small motor 12 which speed motor. 1S preferably of the constant speed type It is a further object of this invention to driven from asuitable source of current such devise an automatic feed mechanism for a as he A. C. lines 3 and 4. Mounted upon ldi g l t d hi h il] ate to the base by sultable means such as a bracket maintain a stable arc while. passing over 13 are the two driven shafts 14 and 15 which large surface irregularities. f p ede rotated in opposite dime- It is a further object of this i ti t tions by means of the motor 12. Thus for devise a welding apparatus in which the anpl he metor may be provided with a electrode will not only be fed forward topml n 6 meshlngwith a gear 17 provided ward the Work but will also be automatically upon the counter shaft 18. Rotatable t withdrawn to pass large irregularities on 'the gether with the gear 17 is a pinion 19 which work Surfmm meshes with a gear 20 secured to the shaft Further objects of this invention will ap 14. Meshing with gear 20 thereis also a pear from the following description inwhlch gear 22 secured to the shaft 15 whereby upon I have set forth the preferred embodiment operation of the motor, 12 the shafts 14 and of my invention. It is to be understoodthat 15 are driven 1n opposite direct-ions. the scope of the invention is to be deter- 0 K mined by reference to the appended claims be advanced or withdrawn from the work b and the state of the prior art. means of a grooved feed roller 26 which is R f in t th d i fixed to a rotatable shaft 27 the shaft 27 be- Figure 1 is a side elevational 'view showlug journaled'm a bracket28 mounted upon The rod or wire electrode 11 is adapted to I ing a device incorporating the principles of the .base 10. For retaining the electrode 11 this invention. against the feed roller 26, an opposed.

Fig. 2 is a plan view of the device as shown grooved pressure roller 29 may be provided in Fig. 1. whereb the electrode may be frictionally Fig. 3 is a cross sectional view. taken retains between the respective eripheries along line 3-3 of Fig. 1. of the rollers 26 and 29. In or er to vary the pressure between these rollers the roller 29 may be mounted upon a suitable adjustable support 30. Thus for example, the support 30 has been shown as pivotally'mounted as at 31 to the bracket 28. The upper end 32 of the support 30 has been extended to engage an adjustable screw 33 threaded in the lug 34 provided on the bracket 28.

work upon which a weld is being made,

mechanism is provided whereby the shaft 27- may be alternately driven either through the shaft 14 orthe shaft 15. Thus mounted upon the shaft 27 there has been provided a gear 36 meshing with-the two pinions 37 and 38 which. are rotatably mounted upon.

the shafts 14 and 15 respectively, Suitabl clutch devices 39 and. 40 have been provided for c-ausin the pinions 37 and. 38 to be rotated by t eir respective shafts 14 and 15. Each of the clutch. devices 39 and 40 may comprise for example complementary clutch members 41 and 42, the clutch member 41 being fixed with respect to the pinion 3'2.

. Clutch member 42has been shown as provided with a suitable line connection 43 with the shaft 14 whereby upon its being shifted longitudinally with respect to the shaft into engagement with the clutch member 41 the pinion 37 may be caused to rotate together with the shaft.

I the clutch members 41 and 42 may comprise opposed frictional surfaces 44 and 45., Resilient means have also been shown for retaining the clutch members normally out of engagement. For example, a compression spring 46 has been shown as normally pressing the two clutch members apart.

With the mechanism as described above it is apparent that upon engagement of one of the clutch devices the electrode 11 will be advanced toward the work while upon engagement of the other clutch device the elec trode will be withdrawn. To control. operation of the clutch devices automatic means has been provided responsive to the condition of the are between the electrode 11 and the work. This automatic control can be bestexplained by reference to Fig. i, in which the electrode 11 has been shown in operative relationship to the worlr 9. @ur

rent is supplied. to the electrode and work from a suitable source such as a generator 47 connected to theelectrode and work by means of'couductors 1 and 25 Afterstriking an are between the electrode 11 and the work 9 it is obvious that the potential ditference across the are will decrease the electrode is moved closer to the work and.

The engaging port-ions of ployed this variation in the potential across 1 the are for automatically controlling the rate of feed of the electrode 11 so that the arc may be maintained in stable condition.

In other words, the potential variations across thearo is maintained between certain practical minimum and maximum'limits by automatically controlling the feed of the Electrode 11 in response to this potential rop.

To accomplish the above results I have emplo ed a solenoid coil 48 which is preferably s unted directly across the electrode 11 and work This solenoid coil 48 is adapted to actuate a pair of contacts 49 and 50 which are connected in series with a second solenoid coil 51, coil 51 being preferably energized from an independent source of current such as thelines 3 and 4 which supply the motor 12. Contact 49 maybe carried for example by a rod 52 having mounted lthereon the solenoid core 53. The contact 49 is normally biased to open position as by utilizing the weight of the core 53 and rod .52. Solenoid 51 is provided with a core 54 which is connected by means of the rod 56, to the two clutch actuating levers 57 and 58. The actuating levers 57 and 58 are shown as connected "together by means of the link 59, and are pivotally mounted to a suitable stationary support as at 60 and 61 respectivel These levers are also provided with suitable fingers 62 and '63 which are adapted to engage the shiftable clutch members 42 of the two clutch devices 39 and 40 whereby upon movement of the lovers in one direction one of the clutch devices will be engaged and upon movement in the other direction the other clutch device will be engaged while the first will be disengaged.

In practice the shaft 14 is driven in such adirection that'when the clutch 39 is engaged the electrode will be set forward, while upon engagement of the clutch 40 the shaft 15 will rotate in a direction to withdraw the electrode away from the work.

arated from the work 9, if the generator current of say 60 volts is connected to the device then a full 66 volt potential difference will exist across the solenoid coil 48 with the result that the current going through this coil will close contacts 49' and 50 and thus close the circuit through the solenoid coil 51. Levers 57 and 58 will then be actuated to engage the clutch 39 and disengageclutch 40, with the result that the electrode 11 will be advanced towards the work. The .arcwill be struck when the electrode contacts with the work at which time the potential across the arc will'drop to a low value as a result of which insuiiicient current will pass through the coil 48 to maintain the wntaots Before an arc is struck and while the electrode 11 is sep- Kid 49 and 50 in closed position so that the circuit through solenoid 51 will be opened. Levers 57 and 58 will then move to a position to disengage clutch 39 and engage clutch 40 whereby the motor drive will withdraw the electrode from the work. As the electrode is withdrawn it is obvious that the potential across the arc will increase, there being a certain maximum value after which the arc will not be stable in operation. However, before the electrode is withdrawn to the point that the arc becomes unstable, the contacts 49 and 50 will again be closed by the solenoid coil 48 to actuate levers 57 and 58 in order to again advance theelectrode. In normal operation alter the arc has been struck and when the electrode is being moved across the work which is being welded, such as a seam between two pieces of sheet metal, the electrode is continuously fed forward and backward so that the average rate of advancement is substantially equal to the rate of consumption of the electrode. It is preferable in accomplishing this result to design the motor drive so that it will advance the electrode at a rate greater.

- the weld,'it is obvious that the ordinary type of automatic electrode control which merely varies the speed of advancement, would permit shorting of the electrode against the work since the rate of consumption would not be sufiicient to keep the end ofthe electrode out of'contact with the work as the arc attempts to travel u the slope 66. of the projection. With the evice of this invenwith the result that the arc is maintained in stable condition and a uniform weld may be made over the entire surface of the projection. In other words, considering the dotted line 67 as the effective locus of a point fixed upon the electrode 11 and ignoring the intermittent movements, this locus will gradually approach the surface of the work 9 but will actually rise to clear the projection 65.

For. convenience the actuating levers 57 Y and 58 are pivotally mounted to a suitable bracket 69 mounted upon the base 10 while the solenoid 51 may likewise be mounted upon the flange 7 0 oi the base. For biasing the levers in a directlon to normally engage secured to the ,rod 52, adjustment being ef fected by the set screw 73.

I claim:

1. In an arc welding system, a welding electrode, a source of welding current, means for feeding said electrode with respect to the workfupon which a weld is to be made, and

""means responsive to variations in potential across the arc for maintaining a given average potential across the electrode and work, and adjustable means for changing the value of said average potential.

2. In an arc welding system, a constant speed electric motor, speed reduction transmission elements connected therewith in cluding a pair of reverse clutches, means for feeding a welding electrode toand from the work operated in opposite directions respectively by said clutches, a pivoted lever arranged to operate the clutches respectively upon opposite way movement, welding arc potential controlled means for moving said lever, and adjustable means for biasing said lever in one direction.

3. In an arc welding system, a constant speed electric motor, speed reduction transmission elements connected therewith including a pair of reverse clutches, means for feeding a welding electrode to and from the work operated in opposite directions respectively by said clutches, a pair of pivoted levers arranged respectively to operate said clutches, a link pivotally connecting said levers, a weight adjustable to move said levers in one direction, and electromagnetic means controlled by the welding arc potential arranged to move said levers in opposition to said weight for alternately throwing said clutches into engagement upon variation of potential.

4. In an arc welding system, a constant speed electric motor, speed reduction trans mission elements connected therewith includmg a pair on reverse clutches, means for feeding a welding electrode to and from the work operated in opposite directions respectively by said clutches, electro-magnetic means controlled by the potential across the welding arc arranged for alternately engagin said clutches upon variation in otentia, whereby either one of said clutc es is at all times engaged to feed said electrode. V

In test-ony whereof, I have'hereunto set my hand.

ALBERT K. HARFORD. 

